Narcissists should be held accountable for most of their actions because they can tell wrong from right and they can refrain from acting. They simply don't care enough about others to put to good use these twin abilities. Others are not sufficiently important to dent the narcissist's indifference or to alter his abusive conduct.
(From the book "Malignant Self-love: Narcissism Revisited" by Sam Vaknin - Click on this link to purchase the print book, or 16 e-books, or 2 DVDs with 12 hours of video lectures on narcissists, psychopaths, and abuse in relationships: http://www.narcissistic-abuse.com/thebook.html)